This disclosure relates to methods of making optical fiber or waveguide lenses.
Optical fibers and waveguides made of glass are often used in optical transmission systems and other optical systems. The machining of the end face of these fibers and waveguides plays a crucial role during the use of these single mode or multimode fibers and waveguides. It is important that the end faces have a particularly uniform surface so that the transition from one element of an optical system to another can be carried out with minimal damping values. It is also important that the end faces of the fibers and waveguides can be produced at predetermined angles and that these angles are reliable and reproducible.
The use of lenses to efficiently couple light into or out of a fiber or waveguide from a source is well known. In determining light coupling efficiency between the source and fiber or waveguide, the shape of the fiber or waveguide end and the amount of light emitted from that end can provide information about the performance of the lensed fiber or waveguide.
One aspect of he present invention features a method of making a lens on an optical fiber comprising providing a laser system having a power density of at least 1015 W/m2 and a laser pulse duration of one picosecond or less; and subjecting the end of an optical fiber to the laser to ablate a portion of the optical fiber such that a desired lens shape is obtained.
Another aspect of the present invention features a method of making a lens on an optical waveguide comprising providing a laser system having a power density of at least 1015 W/m2 and a laser pulse duration of one picosecond or less; and subjecting the end of an optical waveguide to the laser to ablate a portion of the waveguide such that a desired lens shape is obtained.
As used in this invention:
xe2x80x9clensxe2x80x9d means a piece of material, usually glass, and usually curved, used for the refraction of light; and
xe2x80x9cwaveguidexe2x80x9d means a structure that directs the propagation of energy, in the form of a wave, to follow a prescribed path.
An advantage of at least one embodiment of the present invention is the ability to control surface shaping of a fiber or waveguide lens using a laser ablation process with a substantial lack of heating and mechanical stress on the majority of the fiber or waveguide. In comparison to other laser processes that use longer pulse widths, such as excimer lasers, Nd:YAG lasers, and CO2 lasers that have pulse widths of a few nanoseconds and longer, the ultrafast laser processing of the present invention removes material with minimal collateral thermal effects. In making a desired shape, the lack of heating is an advantage over other techniques, such as flame polishing, because it provides the ability to make a desired shape with no reflow.
Another advantage of at least one embodiment of the present invention is that, in contrast to mechanical processes for removing material, a process of the present invention does not apply flexural stress to the end of the fiber or waveguide, which can be an advantage in handling.
Other features and advantages of the invention will be apparent from the following drawings, detailed description, and claims.